One of the primary concerns of the framers was controlling the balance of power. This concern led to the creation of the legislative, executive, and judicial branches of government. It also led to constitutional amendments that defined the responsibilities of the various state governments and the federal government. In the larger question of the relationships between the states, the establishment of a bicameral legislature was designed to balance the power between the larger states and smaller states.
The division of the members of the House of Representatives is based on population with larger states having more representatives and thus the quantity of representatives of those states is more in line with the percentage of the population that they represent.
The division of the members of the Senate is consistent regardless of the size of the state with two members representing each state. This allows for balance and equal voices of the smaller states with the larger ones thus allowing the minority to still have representation.
By dividing various important legislative activities among the two legislatures, such as budget, appropriations, initial bill writing, etc., and then requiring most of them to then be approved by the other chamber before being sent to the president to become law, the framers hoped to create a system of law creation that would represent the majority of the population's interests while still allowing fair voices for the smaller states.